Use an Android cell phone built in GPS with Android OpenCPN and the phones hotspot, to provide a GPS signal for other devices running OpenCPN.
An (old) Android phone with a GNSS receiver will, as rgleason said, do all the job instead of other gadgets. - Install OCPN - Connect the inbound GNSS. - Make a UDP output connection to localhost port 10110 in OCPN. No input.
- Start the phone's hotspot. (Set it to paid connection to avoid massive downloads if you've a SIM card installed. (Not necessary)) - Connect a power cable to the phone and hang it high.
- Connect the OCPN PC/tablet(s) to the hotspot wifi network. - In OCPN make a network UDP input connection to port 10110 and you're done.
PS1: In the case the PC is drowned or else failure the phone's OCPN is still working. PS2: The phone can act as power cheap anchor watch instead of the PC. PS3: Get a cheap GNSS puck/mouse for more redundancy. (Every electronic device in a boat may soon or later fail.)